Thermally-controlled electric snap switch



Feb. 21, 1928. 1,659,862

0. DODGE THERMALLY CONTROLLED ELECTRIC SNAP SWITCH Filed Aug. 10. 1922 5 Sheets-Sheet l V l "FA TOR Feb. 21, 1928. 1,659,862

0. DODGE THERMALLY CONTROLLED ELECTRIC SNAP SWITCH Filed Aug. 10. 1922 3 Sheets$heet 2 mus/V7018,

S Sheets-Sheet 5 O. DODGE THERMALLY CONTROLLED ELECTRIC SNAP SWITCH Filed Aug. 10. 1922 Q v. r

Feb. 21, 1928.

nvm/vm/e Patented Feb. 21, 1928.

OWEN DODGE, OF COLORADO SPRINGS, C ELECTRIC CONTROL COMPANY, OF COLO OF COLORADO.

OLORADO, ASSIGNOR TO THE AUTOMATIC RADO SPRINGS, COLORADO, A CORPORATION THERMALLY-CONTROLLED ELECTRIC SNAP SWITCH.

Application filed August 10, 1922. Serial No. 580,880.

My invention relates to thermally controlled fuel cut-ofi' mechanisms for heated utensils, and with particular reference to circuit breakers for laundry irons.

So far as I am aware the prior art has not disclosed anything which fills the requirements for this particular use as prescribed by commercial manufacturing practice, by the rules of the fire-underwriters, and the electrically heated call of the using public.

termed as being fool proof, which eliminates lost motion in operation, which saves in operating cost the difference between that cost which produces a practical operating temperature and that temperature which usually obtains in the operation of this class of device, together with the entire absence of that nervous mental strain upon the operator caused by the firmly impressed knowledge that destructive temperatures are most likely to occur at any time even though due vigilance has thought to have been taken.

One of the, if not the most, vitally essential requirements in a switch of this class is, to so position and connect the switchclosing lever that it can in no way retard or entirely prevent the switch operating to open the electric circuit.

Any switch of this class, the operation of which can be retarded or prevented by any external cause is, practically, worse than useless. Hence, one of the primany objects of my invention is, to so position the switch closing lever, no matter what form or shape it may be, that it can only function to close the circuit.

The practical features of this invention which I believe to be patentably characteristic thereof are definitely set forth in the appended claims. The invention itself and the construction and mode of operation of the invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which:

Figure 1-, is an elevation of a commercial laundry iron, partly in section, illustrating a practical position for the switch in the cored sole and insole castings of the iron; and particularly the position of the switch operating lever in both the off and on positions of the switch. Fig. 2, is a plan view of Figure 1, and is intended to Show the position of the switch body, position of the switch operating lever in both on and off positions of the switch, and position of the on indicating element in its off position.

Fig. 3, is a plan View of Figure 1, and is intended to show the position of the switch operating lever in its normal position by full lines, its operating limit of swing for throwing the switch to on position by dotted lines, and the indicating element in its on position. Fig. 4, is a sectional elevation of the switch illustrating the essential elements, in operating position, of this particular construction. Fig. 5, is a plan view of the switch complete. Fig. 6, is a sectional plan view of the switch on the line aa Figure 4, and illustrates the relative positions of the contact elements at the instant of either make or break. Fig. 7, is a sectional plan view on the line 6-?) F lgure 4, and is intended to show the relative positions of the ratchet and gravity actuated pawl. Fig. 8, is a plan view of the toggle member which carries the circuit closing element. Fig. 9, is a cross sectional view on the line d-d Figure 8, and shows the method of construction and insulation of the contact making element from the body of the switch. Fig. 10, is an open plan view illustrating the relative positions of the circuit closing elements in the on position. Fig. 11, is an open plan view illustrating the relative positions of the circuit closing elements in the off osition. Fig. 12, is an edge view in the direction of the arrows w-y, Figure 5, indicating means for operatin the switch to the on position with the loose y pivoted switch lever. Fig. 13, is an elevation of the loose member 24 of the switch toggle. Fig. 14, is an elevation ofthe working end 0 the leaf spring 18.

Numeral 1, indicates the sole of a laundry iron. 2, indicates the insole. 3, indicates the heating element. 4, indicates the cover of the iron. 5, indicates the part of the bod element in which the fusible alloy is retaine 6, indicates the upper part of the body element of the switch. 7, indicates a rotatable shaft one end of which dips into the well 5, and is surrounded by the fusible-alloy 17. 8, is a wing member rigidly attached to the lower end of the shaft 7, and is employed to present a greater surface to action of the alloy. 9, is a cover for the well 5, it also forms the lower bearing for the rotatable elements. 10, is a ratchet element rigidly attached to the shaft 7. 11, is an element pivotally mounted upon shaft 7, and to which elements 10-25-25 are rigidly secured, and elements 19-26 and 15 are loosely mounted. 12, is the circuit closing element loosely supported in element 14, and bridges elements 16-16. 13, indicates insulation. 14, indicates the part which loosely supports the circuit closing element 12, and which is rigidly secured to the element 22 but electrically insulated therefrom. 15, is the switch operating lever, loosely pivoted on the element 11, and is operative only in the on direction of the switch. 16-16, are the live terminals of the switch, and are bridged by the element 12 in the on position of the switch. 17, is the fusible-alloy which is retained in the well 5. 18, is aleaf spring which produces the quick snap make and break action through the medium of the toggle elements; this spring functions also as a restraining element, which was originally disclosed and claimed in my pending application filed September 22, 1921, bearing Serial Number 502,483. 19, is a gravity operated pawl which holds the switch in the on position until the alloy allows a rotary motion of element 7, against the restraining force of the spring 18. The pawl 19 permits a free movement of the element 11, and its associated elements, in the direction of closing the electric circuit, and as illustrated, in a clockwise direction, and in an anticlockwise direction, elements 7, 8, 10, 11, 25-25 and 26, move as a unit. 20, is a cover for the switch body 6, and also forms the upper bearing for the rotatable elements. 21, is

the power spring of the switch, and has a greater stored power than the .forces opposing it when the alloy is in a fluid condition, but less power than the forces opposing it when the alloy is in only a softened condition. 22, is one element of the toggle mechanism for producing the quick make and break, and is loosely pivoted between elements 25-25. It also supports elements 14 and 12. 23, is a pivot which is a press fit in 22. 24, is the second element of the toggle mechanism. 25-25, are interchangeable elements which are a press fit upon the element 11, and which serve as bearings for the pivot 23 of the toggle combination. 26 is an indicator which is attached to the upper end of and moves with element 11, and is employed to show when the switch is in the on position. 27, is a spring element for returning the switch lever 15 to off position. 28, is a turned down part of the element 26 for engaging the turned up part 29 of the ele ment 15. 29, is a turned up part of the element 1,5 for engaging the turned down part 28 of the element 26. 30, is a turned down part of the element 15 for engaging the spring 27. 31, indicates means for rigidly securing ratchet 10 to shaft. 7. 32 indicates a heat resisting packing, such as asbestos fibers, employed to prevent oxidation of the alloy, and to prevent the liquid alloy from escaping.

In the commercial application of this switch to electric laundry irons, the sole and insole castings are cored as indicated in Fig.1, and the switch terminals are connected in series with the heating element as indicated in Fig. 2.

The switch is easily retained in position by being clamped between the cover of the iron and the bottom of the cored hole in the sole of the iron. The element 11 protrudes through the cover of the iron. The spring 27 being in position the loosely pivoted handle 15 is placed on 11, indicating element 26 is then pressed upon 11, and the handle of the iron screwed to position. In irons not having handles attached in this manner, aprotective strip of metal would be substituted therefor and attached to the cover by a suitable means.

In using an electric iron embodying this invention; the iron is connected to the circuit by means of a flexible cord in the usual switch is then free to function under any and all conditions. If the switch handle 15 were rigidly attached to 11 and moved with it, should the forward motion of the handle be obstructed, in any manner, the switch could not function, and destructive temperatures could follow. Any switch which does not embody this feature, cannot be considered as being free of the fire-hazard element. It will be seen that the switch operating handle is so placed and formed that the user can easily operate it without removing the hand from the handle of the iron.

I find that the hinged or pivotal parts of this class of switch have a tendency to cut or abrade, and therefore, the practical working life of the switch would be materially shortened. To obviate this condition, I find it of advantage to harden or case-harden the pivotal parts of the toggle elements and the pawl and ratchet; the shaft 7 and angular element 11 appear to withstand the work without hardening.

I am aware that there have been many switches of this general class disclosed; however, I do not know of any combination having been disclosed before this disclosure which fills the three requirements cited in the opening paragraphs of this specification s, bome particularly essential objects of this invention.

Having quite fully described the essential requirements imposed upon a switch of this class, and having illustrated and described my combination of elements for fulfilling these requirements; what I claim as new and patentably characteristic therein, and desire to secure by Letters-Patent, is:

1. In a thermally controlled electric circuit opening switch of the character described; the combination comprising a container of fusible-alloy, a shaft extending out-- wardly from within said container of fusiblealloy, a ratchet element mounted upon said shaft and adapted to turn with said shaft, a rotatable element mounted upon said shaft and resting upon said ratchet, toggle-joint electric circuit closing and opening means mounted upon said rotatable element, a spring element adapted to move the rotatable element in a direction to open said electric circuit, a spring element adapted to press against the last link of the toggle-joint elements and adapted to provide a quick break in opening the electric circuit.

2. In a thermally controlled electric circuit opening switch of the character described; the combination comprising a cupshaped element supporting all the elements of the switch unit, said cup-shaped element being adapted to be clamped and held firmly in operating position by pressure between the cover of an electric iron and the top surface of a cored recess in the sole plate of said electric iron.

3. In a thermally controlled electric circuit opening switch of the character described; comprising in combination a container of fusible-alloy, a shaft extending outwardly from within said container of fusiblealloy, a ratchet element mounted upon said shaft and adapted to turn with said shaft, a rotatable element mounted upon said shaft and resting upon said ratchet, a gravity operated pawl mounted upon said rotatable element and adapted to engage said ratchet.

4. In a thermally controlled switch of the class described; the combination comprising a shaft, a loosely rotatable element mounted upon the shaft, pivot supporting elements rigidly secured to the rotatable element, toggle circuit closin and opening elements loosely pivoted in t e supporting elements, a spring element in operative connection with one link of the toggle elements, a power spring in operative connection with the rotatable element, a switch-closing element loosely connected to operate the rotatable element, a spring element in driving connection with said switch-closing element, and an on indicating element adapted to move with the rotatable element.

5. In a thermally controlled switch of the class described; comprising a shaft, an angular element loosely supported upon the shaft, a toggle element pivotally secured to the angular element, a circuit-closing and opening element loosely supported in one end of the toggle element, electric insulation separating said circuit-closing and opening element from said toggle element, a power element in driving connection with said angular ele- 100 ment, and a loosely-connected circuit-closing switch-operating lever in operative-connection with the angular element.

6. In a thermally controlled switch of the class described; the combination comprising 5 a cup-shaped body element having a restricted lower portion, a cover for the restricted portion enclosing a heat-resisting packing,

a fusible-alloy in the restricted portion, a

shaft dipping into the fusible-alloy and extending upwardly through the cover, a ratchet element rigidly secured to the shaft above the cover, and electric circuit-closing and opening elements rotatably supported by the shaft and ratchet.

7. In a thermally controlled electric circuit opening switch of the character described, having a' fusible-alloy for controlling said electric circuit opening; the combination comprising a container of fusible- 12o alloy, a cover for said container, a heat resisting packing between said cover and said alloy, the enlarged end of a shaft in said container and surrounded by said fusible-alloy, I said shaft extending upwardly through said cover and said packing, and a ratchet element rigidly secured to said shaft above said cover.

8. In a thermally controlled electric circuit opening switch of the character described, having a fusible-alloy for controlsaid ratchet supporting a rotatable element ling a spring actuated automatic electric cira toggle-joint electric circuit closing and cuit opening unit; the combination comprisopening unit mounted upon said rotatable l0 'ing a container of fusible alloy, a shaft exelement, and an indicating element secured '8 tending upwardly from within said fusibleto the top of said rotatable element and alloy, a ratchet element rigidly secured to adapted to move therewith.' saidshaft above said alloy, said shaft and OW'EN DODGE. 

